1. Field of the Invention
The present invention relates to a process for forming an image comprising an inorganic material, and more particularly, it relates to a process for forming a semipermanent sintered image comprising an inorganic material on ceramic materials used for building materials, such as artistic tiles, and ceramic products.
2. Description of the Related Art
Ceramic materials having black-and-white or color images formed on the surface thereof are utilized not only in building materials, such as artistic tiles used on walls in bathrooms and entranceways, but also in ceramic photographs, such as portraits, and accessories, such as pendants and broaches.
As a process for forming an image on the surface of a ceramic material, an electrophotographic process has been known in which a colored toner comprising an inorganic material exhibiting color is applied imagewise to form an image. JP-A No.9-197719 discloses an example of such an electrophotographic process, in which a colored toner image is formed from an electrostatic image having been made by using a colored toner comprising an inorganic material, and the toner image is transferred to an image receiving body.
However, when a multi-color or full color image is to be formed by this process, plural kinds of toners corresponding to the pigments of respective colors are necessarily prepared, e.g., a yellow toner (Y), a magenta toner (M) and a cyan toner (C), and the toners must be designed to have the characteristics of respective pigments. Furthermore, when the colored toner contains iron or an oxide thereof, the toner is liable to turn blackish upon calcining, whereby an image having a desired hue is difficult to obtain.
When a multi-color or full color image is to be formed, it is necessary to use a printer for forming a color image, which is generally expensive.
Another process for forming an image on a ceramic material has also been known, where a transfer sheet having a transfer layer comprising a transfer material including an inorganic pigment is prepared, and the transfer material in the transfer sheet is thermally transferred to the ceramic material to form an image.
However, when an image is formed by the transfer process, while no problem arises when using only a single transfer processing (i.e., monochrome transferring) per one image receiving body, it is difficult to obtain desired hues when a multi-color or full color image is to be formed, and problems arise with respect to resolution and gradation. That is, when plural transfer sheets having different hues are laminated on one image receiving body to obtain a multi-color or full color image, a transfer material used in the second or later transfer processings is deposited on a transfer material that has already been transferred (i.e., a part that should not be colored), whereby desired hues cannot be obtained. This phenomenon is referred to as secondary color fogging, resulting from the facts that the transfer material contains a thermoplastic resin having adherent properties.